"Employers must have some flexibility to train employees and then direct them to do new tasks however a sensible line needs to be drawn especially when an enterprise agreement clearly provides limitations,” Mr Diamond said.

“In this instance, Commissioner Spencer even spent time at the site to understand the new tasks and to consider whether they would fall within the classification. Her process and findings were extremely thorough.

“Aurizon should remember its classifications are there for a reasons and classification creep to the detriment of union members will not be tolerated."